Asymptomatic Malaria Infection and Hidden Parasitic Burden in Gabonese Schoolchildren: Unveiling Silent Co-Infections in Rural and Urban Settings

This study aimed to determine the prevalence of co-infection with malaria and intestinal parasites and assess its association with anemia in school-aged children from rural and urban settlements in Gabon. This cross-sectional study involved afebrile school children recruited at schools between May and June 2021. Blood and stool samples were collected from participants whose parents or legal guardians provided informed consent to participate in the study. Hemoglobin concentration (Hb) was measured using a HemoCue photometer (HemoCue 201, HemoCue, Angelholm, Sweden). Giemsa-stained blood films were examined to detect malaria parasites and any filarial infections, while the merthiolate-iodine concentration (MIC) method was used to identify intestinal parasitic infections (IPI). A total of four hundred and seventy (470) school-aged children were successfully enrolled in this study. The observed prevalence values were as follows: malaria infection at 69.6%, IPIs at 19.1%, filaria at 5.1%, Schistosoma infection at 15.0%, and anemia at 29.0%. Co-infections of malaria with IPIs, filaria, and Schistosoma were present in 12.3%, 4.7%, and 6.6% of the children, respectively. Malaria and filaria infections were associated with residing in Lastourville city (p < 0.05) and were also correlated with age (p < 0.05), whereas IPIs were associated with male gender and living in the city of Lastourville. Anemia was linked to malaria infection (p < 0.05) and was more prevalent among children living in rural areas. The findings of this study indicate that malaria, IPIs, and Schistosoma infections continue to pose a significant public health problem in the study area, even though only malaria infection appeared to be associated with anemia. Nevertheless, these results highlight the need for implementing control measures to reduce the prevalence of malaria, IPIs, filaria, and Schistosoma, particularly in Lastourville.

Parasitic infections during pregnancy in Gabon affect glycosylation patterns of maternal and child antibodies

Antibody glycosylation patterns can affect antibody functionality and thereby contribute to protection against invading pathogens. During pregnancy, maternal antibodies can be transferred through the placenta and contribute to modulating both the mother's and her child's immune responses. Although several studies of IgG glycosylation during pregnancy have been carried out, very few cohorts studied were from sub-Saharan Africa, where exposure to microorganisms and parasites is high. In Lambaréné, Gabon, 106 pregnant women in their third trimester were enrolled into this study. At enrolment, urine, stool, and blood samples were collected from the mothers to assess Schistosoma haematobium (S. haematobium), Plasmodium falciparum (P. falciparum) and other parasite infections. During delivery, cord blood samples were collected. The children were followed, and blood samples were collected at 9 and 12 months of age. IgG Fc glycosylation was measured by liquid chromatography-mass spectrometry, determining fucosylation, galactosylation, sialylation, bisection, and sialylation per galactose (SA/gal). Among the 106 pregnant women, 33 (31%) were infected by at least one parasite. The antibody glycosylation patterns in maternal and cord blood showed distinct profiles when compared to that of infants at 9 and 12 months. IgG galactosylation was higher in maternal/cord blood, while fucosylated IgG was higher in children up to 1 year of age. Maternal parasitic infection was associated with lower IgG2 and IgG3/IgG4 galactosylation in cord blood and lower IgG3/IgG4 galactosylation in children. When maternal IgG galactosylation and, consequently, cord blood were categorized as high, children at 9 and 12 months of age showed higher IgG galactosylation compared to children of mothers with low IgG galactosylation. As IgG Fc galactosylation can have functional consequences, it might provide valuable information for developing effective preventive and treatment strategies for vulnerable populations.

Co-infection of Plasmodium and soil-transmitted helminth among pregnant women in Abaya district, South Ethiopia: A community-based study

Objectives

Co-infection of malaria with helminths poses significant risks, including fetomaternal hemorrhage, fetal growth retardation, spontaneous abortion, and preterm delivery. However, there is a lack of community studies to demonstrate the prevalence of co-infection of helminths with Plasmodium and soil-transmitted helminths (STH) and associated factors among pregnant women in Ethiopia.

Methods

A community-based cross-sectional study was conducted among 287 randomly selected pregnant women in the Abaya district from September to December 2022. Data were collected using a standardized questionnaire. Blood and stool samples were collected from each pregnant woman and data analysis was performed using SPSS. Logistic regression analysis was used to identify associated factors.

Results

The co-infection prevalence of Plasmodium and STH was 19.5% (95% confidence interval [CI]: 14.92-24.08%), where STHs were 40.6% (95% CI: 34.9-46.3%) and Plasmodium was 32.4% (95% CI: 27-37.8%). Hookworm and Plasmodium falciparum were the most commonly identified parasite species. Factors significantly associated with co-infection with Plasmodium and STH included the habit of eating soil (adjusted odds ratio [AOR] = 2.70, 95% CI: 1.36-5.34), not using insecticide-treated bed nets (AOR = 3.47, 95% CI: 1.76-6.85), living near stagnant water (AOR = 2.23, 95% CI: 1.07-4.64), and rural residence (AOR = 2.23, 95% CI: 1.07-5.97).

Conclusions

Interventions should prioritize enhancing sanitation, educating pregnant women on the use of insecticide-treated bed nets, avoiding eating soil, and eliminating stagnant water near homes. More research should be conducted on the area using more advanced methods.

Safety and efficacy of praziquantel in pregnant women infected with Schistosoma haematobium in Lambaréné, Gabon - Clinical results from the randomized, single-blinded, controlled freeBILy-Gabon trial

OBJECTIVES

Despite evidence of praziquantel's (PZQ) safety for treating schistosomiasis in pregnancy, many countries withhold treatment. Only two randomized controlled trials have investigated PZQ in pregnancy, none involving Schistosoma haematobium.

METHODS

Pregnant women during the second trimester in Lambaréné (Gabon) were screened for S. haematobium infection using urine microscopy and circulating anodic antigen detection. Participants positive for either test were randomized (3:1) to single-dose PZQ 40 mg/kg during pregnancy versus no treatment during pregnancy. Investigators were blinded for allocation. Primary outcomes were reduction of egg (egg reduction rate [ERR]) and antigen production (infection reduction rate [IRR]) while explorative outcomes included assessment of cure rate, adverse events, maternal hemoglobin levels, maternal anemia prevalence at delivery, pregnancy outcomes, and newborn anthropometric parameters.

RESULTS

Of 761 women screened 165 were eligible and randomized (intervention n = 124, control n = 41). Of them, 124 completed the study (n = 90 and n = 34, respectively). Treatment led to a significantly higher ERR (95.0% [91-97%] vs 27.0% [-42-63%]) and IRR (95% [91-97%] vs 56% [14-78%]). Common adverse events were dizziness, nausea, and vomiting. Maternal anemia at delivery was significantly lower in the intervention group (odds ratio: 0.40 [0.16;0.96], P = 0.04). No increased risk for adverse pregnancy outcomes was observed.

CONCLUSIONS

This first randomized controlled trial investigating PZQ in pregnant women with S. haematobium found PZQ to be safe, effective, and reducing maternal anemia. We recommend treating confirmed infections to prevent morbidity in pregnant women.

Prevalence of intestinal parasitic infections among the pregnant women in South and South East Asian countries: A systematic review and meta-analysis

Intestinal parasitic infections (IPIs) are a major health concern in resource-limited countries of South/South-East Asian region. Despite posing a potential threat to maternal and fetal health, there is limited data available on the actual burden of IPI among pregnant women. Through this systemic review and meta-analysis, we sought to determine the pooled prevalence of IPI and species-specific prevalence among pregnant women in this region. Subgroup analysis was done by region, stool examination technique, and study settings. Among 220 retrieved studies, 21 studies from 8 countries across the region were found eligible and included in this study. The estimated overall pooled prevalence of IPIs among pregnant women was 43.15% (95% confidence interval: 30.66-56.10). The most prevalent IPI was Ascaris lumbricoides (25.14%) and predominant protozoa was Entamoeba histolytica/dispar (6.96%). In subgroup analysis, the estimated pooled prevalence of IPIs in Nepal, India, Thailand, and Thai-Burmese Border was 40.88%, 28.33%, 55.38%, and 23.78%, respectively. Studies using Kato-Katz technique for stool examination showed the highest estimated pooled IPI prevalence (62.70%). The prevalence of IPI was found to be lower in facility-based studies (38.12%) than that of studies done in the community (66.21%). Considering the high burden of IPI in pregnant women as estimated in our review and the already established impact of IPI infection on maternal health and fetal outcomes, we recommend implementation of the preventive chemotherapy during routine antenatal checkups.

Impact of helminth infections during pregnancy on maternal and newborn Vitamin D and on birth outcomes

Poor birth outcomes in low- and middle income countries are associated with maternal vitamin D deficiency and chronic helminth infections. Here, we investigated whether maternal Schistosoma haematobium affects maternal or cord vitamin D status as well as birth outcomes. In a prospective cross-sectional study of pregnant women conducted in Lambaréné, Gabon, we diagnosed maternal parasitic infections in blood, urine and stool. At delivery we measured vitamin D in maternal and cord blood. S. haematobium, soil-transmitted helminths, and microfilariae were found at prevalences of 30.2%, 13.0%, and 8.8%, respectively. Insufficient vitamin D and calcium levels were found in 28% and 15% of mothers, and in 11.5% and 1.5% of newborns. Mothers with adequate vitamin D had lower risk of low birthweight babies (aOR = 0.11, 95% CI 0.02-0.52, p = 0.01), whilst offspring of primipars had low cord vitamin D levels, and low vitamin D levels increased the risk of maternal inflammation. Maternal filariasis was associated with low calcium levels, but other helminth infections affected neither vitamin D nor calcium levels in either mothers or newborns. Healthy birth outcomes require maintenance of adequate vitamin D and calcium levels. Chronic maternal helminth infections do not disrupt those levels in a semi-rural setting in sub-Saharan Africa.

Eosinophils, basophils and myeloid-derived suppressor cells in chronic Loa loa infection and its treatment in an endemic setting

BACKGROUND

Chronic infection by Loa loa remains an unsolved immunological paradox. Despite harboring subcutaneously migrating adult worms and often high densities of microfilariae, most patients experience only relatively mild symptoms, yet microfilaricidal treatment can trigger life-threatening inflammation. Here, we investigated innate cell populations hypothesized to play a role in these two faces of the disease, in an endemic population in Gabon.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed numbers and activation of eosinophils and basophils, as well as myeloid-derived suppressor cell (MDSC) subsets and associated circulating cytokine levels by flow cytometry in sex- and age-matched L. loa-uninfected (LL-), -amicrofilaraemic (MF-) and -microfilaraemic (MF+) individuals (n = 42), as well as microfilaraemic individuals treated with albendazole (n = 26). The percentage of eosinophils was lower in LL- (3.0%) than in the combined L. loa-infected population, but was similar in MF+ (13.1%) and MF- (12.3%). Upon treatment of MF+, eosinophilia increased from day 0 (17.2%) to day 14 (24.8%) and had decreased below baseline at day 168 (6.3%). Expression of the eosinophil activation marker CD123 followed the same pattern as the percentage of eosinophils, while the inverse was observed for CD193 and to some extent CD125. Circulating IL-5 levels after treatment followed the same pattern as eosinophil dynamics. Basophil numbers did not differ between infection states but increased after treatment of MF+. We did not observe differences in MDSC numbers between infection states or upon treatment.

CONCLUSIONS/SIGNIFICANCE

We demonstrate that both chronic infection and treatment of L. loa microfilaraemia are associated with eosinophil circulation and distinct phenotypical activation markers that might contribute to inflammatory pathways in this setting. In this first ever investigation into MDSC in L. loa infection, we found no evidence for their increased presence in chronic loiasis, suggesting that immunomodulation by L. loa is induced through other pathways.

Detection of Plasmodium falciparum in Saliva and Stool Samples from Children Living in Franceville, a Highly Endemic Region of Gabon

Due to the difficulty of obtaining blood samples, which is the invasive method that is currently used for the detection of Plasmodium spp., alternative diagnostic sampling methods that are effective and non-invasive are needed, particularly for long-term studies. Saliva and stool samples from malaria-infected individuals contain trace amounts of Plasmodium DNA and therefore could be used as alternatives. Malaria was screened using rapid diagnosis tests and confirmed via microscopy. Nested PCR tests targeting the Plasmodium falciparum-specific STEVOR gene were performed for blood, saliva and stool samples that were positive for malaria. Three hundred sixty-seven (367) children were enrolled and eighty (22.22%) were confirmed to be positive for malaria. Matched blood, saliva and stool samples were available for 35 children. By using blood smears as the gold standard for the diagnosis of malaria, our study indicates that Plasmodium DNA was more detectable in blood (100%) than in saliva (22.86%) and stools (14.29%). Applying qPCR to the STEVOR gene to detect Plasmodium falciparum DNA in saliva and stool samples cannot be considered as an alternative to the current malaria detection processes using blood specimens.

Soil-transmitted helminths: A critical review of the impact of co-infections and implications for control and elimination

Researchers have raised the possibility that soil-transmitted helminth (STH) infections might modify the host's immune response against other systemic infections. STH infections can alter the immune response towards type 2 immunity that could then affect the likelihood and severity of other illnesses. However, the importance of co-infections is not completely understood, and the impact and direction of their effects vary considerably by infection. This review synthesizes evidence regarding the relevance of STH co-infections, the potential mechanisms that explain their effects, and how they might affect control and elimination efforts. According to the literature reviewed, there are both positive and negative effects associated with STH infections on other diseases such as malaria, human immunodeficiency virus (HIV), tuberculosis, gestational anemia, pediatric anemia, neglected tropical diseases (NTDs) like lymphatic filariasis, onchocerciasis, schistosomiasis, and trachoma, as well as Coronavirus Disease 2019 (COVID-19) and human papillomavirus (HPV). Studies typically describe how STHs can affect the immune system and promote increased susceptibility, survival, and persistence of the infection in the host by causing a TH2-dominated immune response. The co-infection of STH with other diseases has important implications for the development of treatment and control strategies. Eliminating parasites from a human host can be more challenging because the TH2-dominated immune response induced by STH infection can suppress the TH1 immune response required to control other infections, resulting in an increased pathogen load and more severe disease. Preventive chemotherapy and treatment are currently the most common approaches used for the control of STH infections, but these approaches alone may not be adequate to achieve elimination goals. Based on the conclusions drawn from this review, integrated approaches that combine drug administration with water, sanitation and hygiene (WASH) interventions, hygiene education, community engagement, and vaccines are most likely to succeed in interrupting the transmission of STH co-infections. Gaining a better understanding of the behavior and relevance of STH co-infections in the context of elimination efforts is an important intermediate step toward reducing the associated burden of disease.

The Global Prevalence of Schistosoma mansoni, S. japonicum, and S. haematobium in Pregnant Women: A Systematic Review and Meta-Analysis

Schistosomiasis is a neglected tropical disease affecting 40 million women of childbearing age worldwide. Its global disease prevalence among pregnant women is still unknown. This meta-analysis determined the pooled prevalence of schistosomiasis among pregnant women globally. Additionally, this study also determined the pooled prevalence based on infection intensity based on eggs per gram. Observational studies on the prevalence of schistosomiasis among pregnant patients were obtained from Medline, Scopus, and CINAHL from January 2001 until August 2020. A review of titles and abstracts was done independently by six reviewers. The quality of the included studies was assessed using the Newcastle-Ottawa Scale for case-control, cohort, and cross-sectional studies. A total of 27 studies were included in the meta-analysis and meta-regression. The pooled prevalence of S. haematobium was 13.44 (CI: 8.90-19.80) per 100 observations, while the pooled prevalence of S. mansoni was 12.18 (CI: 4.47-29.12) per 100 observations. The prevalence of S. japonicum infection in one study was 53.54 (CI: 43.23-63.62) per 100 observations. Our results showed a prevailing health problem of schistosomiasis during pregnancy in various countries worldwide. This strengthens the need to conduct more schistosomiasis research, prevention, and control programs in pregnant women.

Effectiveness of antimalarial drug combinations in treating concomitant urogenital schistosomiasis in malaria patients in Lambaréné, Gabon: A non-randomised event-monitoring study

Background

Urogenital schistosomiasis is prevalent in many malaria endemic regions of sub-Saharan Africa and can lead to long-term health consequences if untreated. Antimalarial drugs used to treat uncomplicated malaria have shown to exert some activity against Schistosoma haematobium. Here, we explore the efficacy on concomitant urogenital schistosomiasis of first-line recommended artemisinin-based combination therapies (ACTs) and investigational second-generation ACTs when administered for the treatment of uncomplicated malaria in Gabon.

Methods

Microscopic determination of urogenital schistosomiasis was performed from urine samples collected from patients with confirmed uncomplicated malaria. Egg excretion reduction rate and cure rate were determined at 4-weeks and 6-weeks post-treatment with either artesunate-pyronaridine, artemether-lumefantrine, artesunate-amodiaquine or artefenomel-ferroquine.

Results

Fifty-two (16%) out of 322 malaria patients were co-infected with urogenital schistosomiasis and were treated with antimalarial drug combinations. Schistosoma haematobium egg excretion rates showed a median reduction of 100% (interquartile range (IQR), 17% to 100%) and 65% (IQR, -133% to 100%) at 4-weeks and 6-weeks post-treatment, respectively, in the artesunate-pyronaridine group (n = 20) compared to 35% (IQR, −250% to 70%) and 65% (IQR, -65% to 79%) in the artemether-lumefantrine group (n = 18). Artesunate-amodiaquine (n = 2) and artefenomel-ferroquine combination (n = 3) were not able to reduce the rate of eggs excreted in this limited number of patients. In addition, cure rates were 56% and 37% at 4- and 6-weeks post-treatment, respectively, with artesunate-pyronaridine and no cases of cure were observed for the other antimalarial combinations.

Conclusions

Antimalarial treatments with artesunate-pyronaridine and artemether-lumefantrine reduced the excretion of S. haematobium eggs, comforting the hypothesis that antimalarial drugs could play a role in the control of schistosomiasis.

Trial Registration

This trial is registered with clinicaltrials.gov, under the Identifier NCT04264130.

Performance of Field's Stain Compared with Conventional Giemsa Stain for the Rapid Detection of Blood Microfilariae in Gabon

Filarial infections caused by Loa loa and Mansonella perstans are a considerable public health burden in rural regions of Central Africa. Rapid diagnostic tools for the detection of microfilariae in the blood are needed. Field's stain is a rapid staining technique for microscopic slides originally established for malaria diagnostics. It requires less than 1 minute of staining compared with conventional staining protocols requiring at least 15 to 20 minutes for staining and could thus significantly accelerate diagnostics for human filariasis. Here we evaluated Field's stain as a rapid staining technique in comparison to Giemsa stain for the detection of microfilariae in peripheral blood. Blood smears were collected from 175 participants residing in the region of Lambaréné and Fougamou, Gabon. Each participant's samples were stained in parallel with Field's stain and conventional Giemsa stain. Slides were then microscopically assessed and compared for qualitative and quantitative results by a blinded assessor for the two endemic filarial blood pathogens M. perstans and L. loa. Field's stain shows excellent diagnostic performance characteristics for L. loa microfilariae compared with Giemsa staining. Concordance was favorable for M. perstans although lower than for L. loa. Field's stain offers a rapid alternative to Giemsa stain for detection of L. loa microfilariae in thick blood smears. This could help accelerate diagnostics of blood filarial pathogens in mass screening programs or resource constrained health care institutions with high patient load.

Malaria and Helminthic Co-Infection during Pregnancy in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Malaria and helminthic co-infection during pregnancy causes fetomaternal haemorrhage and foetal growth retardation. This study determined the pooled burden of pregnancy malaria and helminthic co-infection in sub-Saharan Africa. CINAHL, EMBASE, Google Scholar, Scopus, PubMed, and Web of Science databases were used to retrieve data from the literature, without restricting language and publication year. The Joanna Briggs Institute's critical appraisal tool for prevalence studies was used for quality assessment. STATA Version 14.0 was used to conduct the meta-analysis. The I2 statistics and Egger's test were used to test heterogeneity and publication bias. The random-effects model was used to estimate the pooled prevalence at a 95% confidence interval (CI). The review protocol has been registered in PROSPERO, with the number CRD42019144812. In total, 24 studies (n = 14,087 participants) were identified in this study. The pooled analysis revealed that 20% of pregnant women were co-infected by malaria and helminths in sub-Saharan Africa. The pooled prevalence of malaria and helminths were 33% and 35%, respectively. The most prevalent helminths were Hookworm (48%), Ascaris lumbricoides (37%), and Trichuris trichiura (15%). Significantly higher malaria and helminthic co-infection during pregnancy were observed. Health systems in sub-Saharan Africa must implement home-grown innovative solutions to underpin context-specific policies for the early initiation of effective intermittent preventive therapy.

Prevalence and effect of Plasmodium spp. and hookworm co-infection on malaria parasite density and haemoglobin level: a meta-analysis

The dual effects of co-infection of Plasmodium spp. and hookworm on malaria remain under debate. This study investigated prevalence, prevalence odds ratio (POR) of co-infection and impact of co-infection on malaria parasite density and haemoglobin levels in comparison to Plasmodium mono-infection. The protocol for this systematic review and meta-analysis is registered at PROPERO under ID: CRD42020202156. Relevant literatures were obtained from PubMed, ISI Web of Science, and Scopus on 25 December 2020. Mean difference (MD) and confidence interval (CI) of malaria parasite density and haemoglobin were compared using a random effect model. Heterogeneity was assessed using Cochrane Q and I2 statistics. Publication bias was determined by visualising funnel plot asymmetry. Of 1756 articles examined, 22,191 malaria cases across 37 studies included 6096 cases of co-infection of Plasmodium spp. and hookworm. The pooled prevalence was 20% (95% CI 15-26%, I2 99.6%, 37 studies) and was varied in terms of geographical region. Co-infection occurred by chance (OR 0.97, p 0.97, 95% CI 0.73-1.27, I2 95%, 30 studies). The mean malaria parasite density for co-infection (478 cases) was similar to Plasmodium mono-infection (920 cases) (p 0.24, MD 0.86, 95% CI - 0.58-2.29, I2 100%, 7 studies). The mean haemoglobin level for co-infection (90 cases) was similar to Plasmodium mono-infection (415 cases) (p 0.15, MD - 0.63, 95% CI - 1.49-0.23, I2 98%, 4 studies). Co-infection was common and occurred by chance but varied by geographic region. Further studies are required to investigate the mechanism of hookworm infection on malaria severity. Additionally, detection of hookworm infections among patients with malaria in endemic areas of both diseases is recommended to prevent severe malaria.

Prevalence of Intestinal Parasitic Infections and Their Associated Risk Factors among Pregnant Women Attending Antenatal Care Center at Woreilu Health Center, Woreilu, Northeast Ethiopia

Background

Intestinal parasitic infections (IPIs) affect millions of pregnant women worldwide and if left untreated can cause adverse effects for mothers, fetuses, and newborns. This study was aimed at determining the prevalence and associated risk factors of intestinal parasitic infections among pregnant women in Woreilu, Northeast Ethiopia.

Methods

A cross-sectional study was conducted in Woreilu Health Center from October 2018 to February 2019. A convenient sampling technique was used to select the study subjects. The data related to the sociodemographic information and associated risk factors were collected by the interview technique, and fresh stool samples were collected from each pregnant woman. The microscopic examination of the stool samples was done by using direct wet mount preparations in normal saline and formol ether concentration techniques. Descriptive statistics and binary logistic regression were used. A p value < 0.05 was taken as statistically significant.

Results

A total of 331 pregnant women were included. The mean ± standard deviation of age of the participants was 26.3 ± 5.96 years ranging between 16 and 43 years. The overall prevalence of IPIs was 144 (43.5%) with the predominance of E. histolytica/dispar (44.4%) followed by A. lumbricoides (15.7%). Being a student (AOR = 3.35, 95% CI: 1.01-11.09, p = 0.047), second trimester (AOR = 3.94, 95% CI: 1.46-10.64, p = 0.007), third trimester (AOR = 3.32, 95% CI: 1.15-9.6, p = 0.027), and using spring water for drinking (AOR = 2.91, 95% CI: 1.62-5.22, p ≤ 0.001) were significantly associated with IPIs.

Conclusion

The prevalence of IPIs was high in this study. Being a student, second and third trimester, and using spring water for drinking were associated factors with IPIs. Therefore, improving the sanitation of the students and providing clean drinking water for the women should be strengthened. Screening women and providing health education during their antenatal care (ANC) visits are also recommended.

Circulating IL-6, IL-10, and TNF-alpha and IL-10/IL-6 and IL-10/TNF-alpha ratio profiles of polyparasitized individuals in rural and urban areas of gabon

Malaria, blood-borne filarial worms and intestinal parasites are all endemic in Gabon. This geographical co-distribution leads to polyparasitism and, consequently, the possibility of immune-mediated interactions among different parasite species. Intestinal protozoa and helminths could modulate antimalarial immunity, for example, thereby potentially increasing or reducing susceptibility to malaria. The aim of the study was to compare the cytokine levels and cytokine ratios according to parasitic profiles of the population to determine the potential role of co-endemic parasites in the malaria susceptibility of populations. Blood and stool samples were collected during cross-sectional surveys in five provinces of Gabon. Parasitological diagnosis was performed to detect plasmodial parasites, Loa loa, Mansonella perstans, intestinal helminths (STHs) and protozoan parasites. Nested PCR was used to detect submicroscopic plasmodial infection in individuals with negative blood smears. A cytometric bead array was used to quantify interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-α in the plasma of subjects with different parasitological profiles. Median IL-6 and IL-10 levels and the median IL-10/TNF-α ratio were all significantly higher among individuals with Plasmodium (P.) falciparum infection than among other participants (p<0.0001). The median TNF-α level and IL-10/IL-6 ratio were higher in subjects with STHs (p = 0.09) and P. falciparum-intestinal protozoa co-infection (p = 0.04), respectively. IL-6 (r = -0.37; P<0.01) and IL-10 (r = -0.37; P<0.01) levels and the IL-10/TNF-α ratio (r = -0.36; P<0.01) correlated negatively with age. Among children under five years old, the IL-10/TNF-α and IL-10/IL-6 ratios were higher in those with intestinal protozoan infections than in uninfected children. The IL-10/TNF-α ratio was also higher in children aged 5–15 years and in adults harbouring blood-borne filariae than in their control counterparts, whereas the IL-10/IL-6 ratio was lower in those aged 5–15 years with filariae and intestinal parasites but higher in adults with intestinal parasitic infections. Asymptomatic malaria is associated with a strong polarization towards a regulatory immune response, presenting high circulating levels of IL-10. P. falciparum/intestinal protozoa co-infections were associated with an enhanced IL-10 response. Immunity against malaria could differ according to age and carriage of other parasites. Helminths and intestinal protozoa can play a role in the high susceptibility to malaria currently observed in some areas of Gabon, but further investigations are necessary.

The current epidemiological transition of malaria observed in Gabon included, for example, a shift in the at-risk population from children aged less than 5 years old to older children aged 5–15 years. Another consequence was the increasing number of cases of infection among adults. In view of these findings, it is important to explain this phenomenon of epidemiological modification of malaria in Gabon. Intestinal parasites and blood filariasis are endemic in Gabon. These parasites are described to alter the malaria immune response and can be implicated in the susceptibility of individuals to malaria. In Gabon, malaria presents a heterogeneous repartition. Thus, in the present study, we investigated the role of co-endemic parasitosis in the alteration of the malarial immune response by comparing Th1 (IL-6 and TNF-α) and Th2/Treg (IL-10) cytokine production between mono- and co-parasitized individuals in many localities with different epidemiological patterns of malaria. Microscopic analyses and rapid antigenic tests were performed for malaria diagnosis. The nested PCR technique was used to demonstrate the submicroscopic parasitaemia of Plasmodium sp. Then, once groups with different parasitological profiles were constituted, IL-6, IL-10 and TNF-α levels were measured in the plasma of individuals. Th2/Th1 ratios, which can indicate the level of susceptibility of individuals to malaria, were calculated. We observed that there was no interaction between Plasmodium sp. and co-endemic parasites in the present study. However, the high Th2/Th1 cytokine ratio among patients with intestinal protozoa seems to suggest that these intestinal parasites could also play a role in susceptibility to malaria as they do for helminths.

Schistosomiasis in Gabon from 2000 to 2021 - A review

INTRODUCTION

Schistosomiasis is a public health issue of concern in Gabon, with the disease being reported from all regions of the country. The topic has been of interest for the local researchers and physicians for over two decades. The objective of this narrative review was to provide an overview of the research activities in the area from 2000 to early 2021.

METHODS

We performed a narrative literature review. The search strategy was designed to get a broad overview of the different research topics on schistosomiasis and the national control programme, and included grey literature.

RESULTS

A total of 159 articles was screened, and 42 were included into the review in addition to the grey literature. During the past two decades, the work on schistosomiasis originated from five out of the nine provinces of the country, with diverse aspects of the disease investigated; including immunology, epidemiology, diagnosis and treatment. Several studies investigated various aspects of schistosomiasis-related morbidity in the respective study populations. The body of work demonstrates that much effort was made to understand the details of the host immune response to schistosomiasis, and the immune profile changes induced in patients treated with praziquantel. Although some MDA campaigns were conducted in the country; little, however, is known on the epidemiological situation of the disease, particularly of its distribution within the population, as well as co-infections with other parasitic diseases also endemic in the area.

CONCLUSION

Progress has been made over the past two decades in the understanding of schistosomiasis in the country, including disease-related morbidity and its interaction with other parasitic infections, and the immunology and epidemiology of the disease. However, for optimising control of the disease, there is a need to fine-tune these findings with detailed local epidemiological and malacological data. We call for such studies to accomplish the knowledge of schistosomiasis in the country, particularly in areas of moderate or high endemicity, and recommend this approach to comparable schistosomiasis-endemic areas elsewhere.

Prevalence of Intestinal Parasitic Infections and Associated Risk Factors among Pregnant Women Attending Prenatal Care in the Northwestern Ethiopia

Intestinal parasitic infections (IPIs) are the common health problems in developing countries with low socioeconomic and poor living conditions. IPIs affect millions of pregnant women worldwide and may lead to adverse maternal and fetal effects. The present study was aimed at determining the prevalence and associated risk factors of IPIs among pregnant women in Ethiopia. A hospital-based cross-sectional study involving 384 pregnant women was conducted from November 2018 to March 2019. Relevant information on potential risk factors associated with IPIs was gathered using a semistructured questionnaire. Stool samples were collected and examined using wet mount and formol-ether concentration techniques. Logistic regression was used to evaluate the possible association between dependent and independent variables. The overall prevalence of IPIs was 36.7%. Seven species of parasites were identified. The most prevalent intestinal protozoan parasite identified was Entamoeba histolytica/dispar (9.6%) followed by Giardia intestinalis (8.9%). The predominant helminth parasite identified was Ascaris lumbricoides (8.6%), followed by hookworm (5.2%), Taenia spp. (3.6%), Strongyloides stercoralis (1.3%), and Schistosoma mansoni (1.04%). Six pregnant women (1.56%) had infection by two parasite species. The odds of IPIs were higher among illiterates (AOR = 4.63), lowest monthly income earners (AOR = 3.49), primigravida (pregnant for the first time) (AOR = 2.04), those who used unboiled well/stream/river water for drinking (AOR = 14.55), ate soil (AOR = 2.32), and consumed raw vegetables (AOR = 1.91). The prevalence of IPIs in the study subjects was substantially high. Thus, screening of the women for IPIs and providing health education during their antenatal care (ANC) visit are recommended to prevent possible adverse maternal and fetal effects resulting from these infections.

Global prevalence of intestinal parasitic infections and associated risk factors in pregnant women: a systematic review and meta-analysis

BACKGROUND

Intestinal parasitic infections (IPIs) during pregnancy, if left untreated, can cause adverse effects for the mothers, foetuses and newborns. However, limited information is available about the global status of IPIs in pregnant women. Here we undertook a meta-analysis to estimate the global prevalence of IPIs and associated risk factors in pregnant women.

METHODS

We searched the PubMed, Science Direct, Scopus, Web of Science and Google Scholar databases for relevant studies that were published between 1 January 1987 and 30 December 2019. A random effects meta-analysis model was used to estimate the pooled prevalence, odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

A total of 114 studies comprising 98 342 pregnant women across 35 countries were included in the systematic review and meta-analysis. Among IPIs identified from pregnant women, three helminth infections (hookworm 19% [95% CI 15 to 23], Ascaris lumbricoides 17% [95% CI 13 to 21] and Trichuris trichiura 11% [95% CI 7 to 16]) and three protozoan infections (Blastocystis sp. 21% [95% CI 4 to 46], Entamoeba histolytica/dispar 9% [95% CI 3 to 19] and Giardia sp. 8% [95% CI 4 to 13]) were identified as the most prevalent intestinal parasites. Moreover, we found that there was a significant association between IPIs with increased risk of anaemia in pregnant women (OR 2.65 [95% CI 2.08 to 3.37]). The prevalence of IPIs was slightly higher in geophagic pregnant women compared with controls, but this was not significant (OR 1.22 [95% CI 0.87 to 1.71]). According to species, the pooled OR of A. lumbricoides infection had a significantly higher risk in geophagic pregnant women compared with controls (OR 2.66 [95% CI 1.37 to 5.16]). There was a positive relationship between the high prevalence of IPIs in pregnant women living in rural areas compared with urban residents (OR 3.36 [95% CI 1.57 to 7.19]).

CONCLUSIONS

The current review revealed a relatively high prevalence of IPIs in pregnant women, especially in some low- and middle-income countries. These results suggest a need for improved prevention and control efforts to reduce the health risks to pregnant women.

Exploratory analysis of the effect of helminth infection on the immunogenicity and efficacy of the asexual blood-stage malaria vaccine candidate GMZ2

Background

Helminths can modulate the host immune response to Plasmodium falciparum and can therefore affect the risk of clinical malaria. We assessed here the effect of helminth infections on both the immunogenicity and efficacy of the GMZ2 malaria vaccine candidate, a recombinant protein consisting of conserved domains of GLURP and MSP3, two asexual blood-stage antigens of P. falciparum. Controlled human malaria infection (CHMI) was used to assess the efficacy of the vaccine.

Methodology

In a randomized, double-blind Phase I clinical trial, fifty, healthy, lifelong malaria-exposed adult volunteers received three doses of GMZ2 adjuvanted with either Cationic Adjuvant Formulation (CAF) 01 or Alhydrogel, or a control vaccine (Rabies) on days (D) 0, D28 and D56, followed by direct venous inoculation (DVI) of 3,200 P. falciparum sporozoites (PfSPZ Challenge) approximately 13 weeks after last vaccination to assess vaccine efficacy. Participants were followed-up on a daily basis with clinical examinations and thick blood smears to monitor P. falciparum parasitemia for 35 days. Malaria was defined as the presence of P. falciparum parasites in the blood associated with at least one symptom that can be associated to malaria over 35 days following DVI of PfSPZ Challenge. Soil-transmitted helminth (STH) infection was assessed by microscopy and by polymerase chain reaction (PCR) on stool, and Schistosoma infection was assessed by microscopy on urine. Participants were considered as infected if positive for any helminth either by PCR and/or microscopy at D0 and/or at D84 (Helm+) and were classified as mono-infection or co-infection. Total vaccine-specific IgG concentrations assessed on D84 were analysed as immunogenicity outcome.

Main findings

The helminth in mono-infection, particularly Schistosoma haematobium and STH were significantly associated with earlier malaria episodes following CHMI, while no association was found in case of coinfection. In further analyses, the anti-GMZ2 IgG concentration on D84 was significantly higher in the S. haematobium-infected and significantly lower in the Strongyloides stercoralis-infected groups, compared to helminth-negative volunteers. Interesting, in the absence of helminth infection, a high anti-GMZ2 IgG concentration on D84 was significantly associated with protection against malaria.

Conclusions

Our results suggest that helminth infection may reduce naturally acquired and vaccine-induced protection against malaria. Vaccine-specific antibody concentrations on D84 may be associated with protection in participants with no helminth infection. These results suggest that helminth infection affect malaria vaccine immunogenicity and efficacy in helminth endemic countries.

Helminths, mainly because of their immune regulatory effects, are able to impact the response induced by vaccines. In the context of clinical trial designs that measure accrual of natural infections during follow up or outcome of controlled human malaria infection (CHMI), their effect on vaccine efficacy can be measured. Indeed, most of such clinical trials on malaria vaccine candidates conducted in Africa, especially where the prevalence of helminths is high, have shown a certain limit in their efficacy and immunogenicity, as compared to results observed in European and U.S volunteers. The present analysis assessed the effect of helminths on GMZ2, a malaria vaccine candidate. We found a high level of anti-GMZ2 antibodies among volunteers not infected with helminths and protected against CHMI, indicating efficacy of the candidate vaccine in this population. We found a species-dependent effect of helminths on the level of post-immunization GMZ2-specific IgG concentration, and an association of helminths with an early onset of malaria in CHMI. Our findings reveal that helminths are associated with immunogenicity and may decrease the protective effect of antibodies induced by vaccination. Helminth infection status shall be determined when measuring the immunogenicity and efficacy of malaria vaccine candidates in helminth endemic countries.

Focused Assessment with Sonography for Urinary Schistosomiasis (FASUS)-pilot evaluation of a simple point-of-care ultrasound protocol and short training program for detecting urinary tract morbidity in highly endemic settings

BACKGROUND

Urogenital schistosomiasis (UGS) causes inflammation and fibrosis of the urinary tract. In resource-limited settings, affordable tools for morbidity assessment in clinical care are needed. Point-of-care ultrasound has not yet been validated for UGS-related pathology.

METHODS

We developed a protocol for Focused Assessment with Sonography for Urinary Schistosomiasis (FASUS), assessing pathology of the bladder wall, ureters and kidneys. Following standardized training, two clinicians performed FASUS on children and adults with hematuria in Lambaréné, Gabon. Recorded ultrasound clips were remotely reviewed by two ultrasound experts as a diagnostic reference.

RESULTS

In 2015 and 2016, scans were performed in 118 patients. The image quality was sufficient in 90% of bladder views and more than 97% of kidney views. UGS-compatible pathology was detected in 51/118 (43%) by the operator and in 46/107 (43%) by the experts among baseline scans of sufficient quality. Inter-rater agreement between operators and experts was very good (κ > 0.8) for hydronephrosis and good (κ > 0.6) for bladder wall thickening.

CONCLUSIONS

FASUS is a promising clinical, point-of-care tool for detecting UGS-related urinary tract morbidity in symptomatic patients. Based on larger validation studies, appropriate diagnostic and therapeutic algorithms for the use of FASUS should be established.

Association of low birth weight and polyparasitic infection during pregnancy in Lambaréné, Gabon

OBJECTIVE

To report the prevalence of polyparasitism during pregnancy in the Lambaréné region of Gabon and its association with newborn birth weight.

METHOD

Pregnant women in their third trimester were recruited in a prospective study between November 2011 and March 2015. Parasite infection status was assessed microscopically in stool, urine and blood samples. Maternal demographic and obstetrical characteristics and newborns anthropometric data were collected. Multivariable logistic regression was used to assess the association between low birth weight and polyparasitism.

RESULTS

678 of 927 pregnant women were included for analysis with mean age (SD) of 25 (6.8) years. The analysis showed that 69% (468/678) were infected with at least one parasite (Plasmodium spp., Schistosoma spp., soil-transmitted helminths, filarial infections). This comprised of 38% with monoparasitism and 31% polyparasitism. The proportion of newborn babies with a weight below 2500 g (LBW) in our study was 21% (142/678). Compared to pregnant women without infection, women with monoparasitic infection had adjusted Odds Ratio confidence interval 95% CI (aOR [95%CI]) of 1.6 [0.95-2.73], those with two parasites had aOR 95%CI of 2.63 [1.51-4.62], and those with more than two parasites had aOR of 5.08 [2.5-10.38] for delivering a newborn with low birth weight.

CONCLUSION

In Lambaréné, an endemic area for multiple parasite infections, there is a high prevalence of polyparasitism in pregnant women. Polyparasitism is associated with low birth weight. Therefore, there is an urgent need for active screening and treatment of parasite infections in pregnant women to assess the potential public health benefit of such interventions.

Magnitude of parasitic infections and associated factors among pregnant women at health facilities in Hawassa, Southern Ethiopia

Background: Intestinal parasitic infections (IPIs) are common problems during pregnancy, with adverse outcomes including low birth weight and prenatal mortality. The burden of parasitic infections and its impacts are high among pregnant women in developing countries like Ethiopia. Therefore, this study aimed to assess the burden and associated factors of parasitic infections. Methods: A facility-based cross-sectional study was conducted among 365 randomly selected women attending antenatal clinic at five selected health facilities. Data was collected by a pre-tested questionnaire and stool specimens were collected in clean plastic containers. A combination of direct microscopy and the formol-ether concentration technique was used as soon as the specimen collected. Data entry and analysed for descriptive and logistic regression models by SPSS v.23. The result declared as statistically significant at p < 0.05.   Results: The overall prevalence of IPI was 161 (45.9%). The most frequently identified parasites were Ascaris lumbricoides (27.9%), Schistosoma species (13.7%), Trichuris trichiura (5.1%), Hookworm (4.8%), and Taenia species. (1.4%). The IPIs were associated with women having no formal education [AOR=2.19, 95% CI: 1.05-4.57] or elementary school education [AOR=1.90, 95% CI: 1.11-3.27], as compared with high school educated and above. Monthly income of less than 1920 Ethiopian birr [AOR=2.06, 95% CI: 1.28-3.31], sharing a latrine with neighbours [AOR=1.83, 95% CI: 1.14-2.93], using lake water for washing clothes [AOR=2.24, 95% CI: 1.34-3.74], habit of eating raw vegetables [AOR=2.26, 95% CI: 1.30-3.92] were associated with IPI as compared to their counterparts. Conclusions: Nearly half of the pregnant women were infected with IPs. The health facilities and clinicians need to focus on prevention of IPIs by early diagnosis, treating lake water before use, promote proper latrine utilization and provision of pertinent health education as part of ante-natal care service. It is important to minimize the impact of IPIs on pregnant women and their child.

Development of sustainable research excellence with a global perspective on infectious diseases: Centre de Recherches Médicales de Lambaréné (CERMEL), Gabon

Medical research in sub-Saharan Africa is of high priority for societies to respond adequately to local health needs. Often enough it remains a challenge to build up capacity in infrastructure and human resources to highest international standards and to sustain this over mid-term to long-term periods due to difficulties in obtaining long-term institutional core funding, attracting highly qualified scientists for medical research and coping with ever changing structural and political environments. The Centre de Recherches Médicales de Lambaréné (CERMEL) serves as model for how to overcome such challenges and to continuously increase its impact on medical care in Central Africa and beyond. Starting off as a research annex to the Albert Schweitzer Hospital in Lambaréné, Gabon, it has since then expanded its activities to academic and regulatory clinical trials for drugs, vaccines and diagnostics in the field of malaria, tuberculosis, and a wide range of poverty related and neglected tropical infectious diseases. Advancing bioethics in medical research in Africa and steadily improving its global networks and infrastructures, CERMEL serves as a reference centre for several international consortia. In close collaboration with national authorities, CERMEL has become one of the main training hubs for medical research in Central Africa. It is hoped that CERMEL and its leitmotiv “to improve medical care for local populations” will serve as an inspiration to other institutions in sub-Saharan Africa to further increase African capacity to advance medicine.

Maternal Hookworm Infection and Its Effects on Maternal Health: A Systematic Review and Meta-Analysis

Hookworm is an intestinal parasite that infects nearly 230 million people, with another 5.1 billion at risk, especially in poverty-stricken tropical and subtropical regions. Pregnancy is an especially vulnerable time for hookworm infection because of its effect on both maternal and subsequently fetal health. A systematic review and meta-analysis was conducted. The meta-analysis was performed on the association between maternal hookworm and maternal anemia, as well as maternal hookworm coinfection with malaria. The prevalence of hookworm ranged from 1% to 78% in pregnant women, whereas malaria prevalence ranged from 11% to 81%. Pregnant women with hookworm infection were more likely to have anemia (combined odds ratio [cOR] 2.55 [2.20, 2.96], P < 0.001). In addition, pregnant woman with hookworm were more likely to have malaria coinfection (cOR 1.60 [1.38, 1.86], P < 0.001). Other effects on maternal and child health were investigated and summarized without systematic review or meta-analysis because of the limited study numbers. Despite current deworming recommendations in pregnant women, heavy hookworm burden, coinfection with malaria, and subsequent anemia persist. Although this is likely due, in part, to a lack of implementation of preventive chemotherapy, additional interventions such as health education, proper waste management, or linking malaria and soil-transmitted helminth treatment and prevention programs may also be needed. Further investigations on maternal-child outcomes as a result of hookworm infection during pregnancy will highlight public health interventional targets to reduce morbidity in pregnant women and children globally.

Safety and immunogenicity of co-administered hookworm vaccine candidates Na-GST-1 and Na-APR-1 in Gabonese adults: a randomised, controlled, double-blind, phase 1 dose-escalation trial

BACKGROUND

Hookworms cause substantial morbidity in children and women of reproductive age. The control strategy of mass drug administration is suboptimal, hence the need for a vaccine. Necator americanus aspartic protease-1 (Na-APR-1) and N americanus glutathione S-transferase-1 (Na-GST-1) are involved in the digestion and detoxification of haemoglobin in the hookworm digestive tract. In animal models, vaccination against these antigens resulted in protection from challenge infection. Both vaccine candidates were shown to be safe and well tolerated when administered separately to healthy adults. We assessed the safety and immunogenicity of co-administered Na-GST-1 and Na-APR-1 (M74) vaccines in healthy Gabonese adults.

METHODS

This randomised, controlled, double-blind, phase 1, dose-escalation trial was done at the Centre de Recherches Médicales de Lambaréné, in a region of Gabon where N americanus and other helminths are prevalent. Healthy adults aged 18-50 years and living in Lambaréné or the surrounding areas were recruited to the study. Participants were enrolled consecutively into two dose cohorts (30 μg or 100 μg of the experimental vaccines) and randomly assigned in blocks (block size four) to receive three doses of either co-administered Na-GST-1 plus Na-APR-1 (M74; 30 μg or 100 μg of each), adjuvanted with Alhydrogel (aluminium hydroxide gel suspension) together with an aqueous formulation of glucopyranosyl lipid A, or hepatitis B vaccine plus saline (control group). Vaccines were administered intramuscularly on days 0, 28, and 180. The primary endpoint was safety, with immunogenicity a secondary endpoint. The intention-to-treat population was used for safety analyses, whereas for immunogenicity analyses, the per-protocol population was used (participants who received all scheduled vaccinations). Control vaccine recipients for both dose cohorts were combined for the analyses. The trial is registered with ClinicalTrials.gov, NCT02126462.

FINDINGS

Between Oct 27, 2014, and Jan 31, 2015, 56 individuals were screened for eligibility, of whom 32 were enrolled and randomly assigned to one of the three study groups (12 each in the 30 μg and 100 μg experimental vaccine groups and eight in the control group). Both study vaccines were well tolerated in both dose groups. The most common adverse events were mild-to-moderate injection-site pain, headache, myalgia, and nausea. No severe or serious adverse events related to the vaccines were recorded. 52 unsolicited vaccine-related adverse events occurred during the study, but there was no difference in frequency between vaccine groups. IgG antibodies were induced to each of the vaccine antigens, with mean IgG levels increasing after each vaccination. Vaccination with 100 μg of each vaccine antigen consistently induced IgG seroconversion (IgG levels above the reactivity threshold). Peak IgG responses were observed 2 weeks after the third vaccine dose for both antigens, with all participants who received the 100 μg doses seroconverting at that timepoint. IgG levels steadily declined until the final study visit 6 months after the third vaccination, although they remained significantly higher than baseline in the 100 μg dose group.

INTERPRETATION

Vaccination with recombinant Na-GST-1 and Na-APR-1 (M74) in healthy adults living in N americanus-endemic areas of Gabon was safe and induced IgG to each antigen. To our knowledge, this study is the first to report results of Na-APR-1 (M74) co-administered with Alhydrogel in participants from an N americanus-endemic area. Further clinical development of these vaccines should involve efficacy studies.

FUNDING

European Union Seventh Framework Programme.

Impact of Helminth Infections during Pregnancy on Vaccine Immunogenicity in Gabonese Infants

Helminth infections are common in sub-Saharan Africa. Besides direct clinical effects, a bias towards a T helper type 2 (Th2) cell immune response is observed. The consequences of parasite infection during pregnancy for the mother and particularly for the fetus and the newborn can be severe and may include impaired immune response during acute infection and vaccination. Here, we present data of immune responses to vaccines given within the expanded program on immunization (EPI) of infants born to helminth infected or non-infected mothers. The study was conducted in Lambaréné and surroundings, Gabon. Maternal helminth infection was diagnosed microscopically using the Kato-Katz method for soil-transmitted helminths (STH), urine filtration for Schistosoma haematobium infections and the saponin-based method for filarial infections. Plasma antibody levels to different vaccine antigens were measured in mothers and their offspring by enzyme-linked immunosorbent assay (ELISA) at different timepoints. We found 42.3% of the mothers to be infected with at least one helminth species. Significantly lower anti-tetanus toxoid immunoglobulin (Ig) G was detected in the cord blood of infants born to helminth infected mothers. Following vaccination, immune responses of the infants to EPI vaccines were similar between the two groups at nine and 12 months. Even though infection with helminths is still common in pregnant women in Gabon, in our setting, there was no evidence seen for a substantial effect on infants’ immune responses to vaccines given as part of the EPI.

Epidemiology of Schistosomiasis and Soil-Transmitted Helminth Coinfections among Schoolchildren Living in Lambaréné, Gabon

Schistosomiasis is a parasitic infection highly prevalent in Central Africa where it is co-endemic with many other parasitic infections, including soil-transmitted helminths (STHs). For its optimal control, there is a need of descriptive epidemiological data for each endemic region. The objective of the present study was to determine the epidemiological situation around schistosomiasis in Lambaréné, Gabon. A cross-sectional study was conducted among schoolchildren. One urine sample per day was collected on three consecutive days for the diagnosis of schistosomiasis using a urine filtration technique. One stool sample was collected for the detection of Schistosoma spp. and STH spp. eggs using the Kato-Katz technique, and for larvae, using the coproculture technique. A total of 614 schoolchildren were included in the analysis. The overall prevalence of schistosomiasis and STH infections was 26% (159/614) and 15% (70/473), respectively. Human-freshwater contact was the main risk factor for schistosomiasis in the area (relative risk (RR) = 2.96 [2.20-4.00], P < 0.001). Hematuria (RR = 5.53 [4.30-7.10], P < 0.001) and proteinuria (RR = 2.12 [1.63-2.75], P < 0.001) as well as infection with Trichuris trichiura (RR = 1.86 [1.33-2.61], P = 0.002) and Ascaris lumbricoides (RR = 1.96 [1.19-3.21], P = 0.039) were associated with an increased risk of schistosomiasis. Trichuris trichiura was the highest prevalent STH species in the area. Our study reports a moderate prevalence for schistosomiasis with human-water contact as the main risk factor, whereas the prevalence of STH infections appears to be low. Our results stress the need for the implementation of WHO recommendations for schistosomiasis control.

Anaemia in asymptomatic parasite carriers living in urban, rural and peri-urban settings of Gabon

Background

This cross-sectional study was carried out in different settlements of Gabon to determine the influence of single or multiple parasite carriage on haemoglobin (Hb) levels.

Methods

Between April 2015 and June 2016, healthy volunteers from urban, peri-urban and rural areas were screened for malaria, blood filariasis and intestinal parasitic infections using microscopic methods. Hb concentration was measured with a Hemocue analyser. The association between parasite carriage and anaemia was assessed.

Results

Among the 775 volunteers examined, 319 (41.2%) were from rural villages and 76.0% were adults. Filariasis, intestinal parasitic infections, Plasmodium falciparum and polyparasitism were detected in 15.6, 14.6, 9.5 and 6.8% of participants, respectively. Anaemia prevalence was 72.6%, with rates of mild, moderate and severe anaemia being 30.9, 61.1 and 8.0%, respectively. The median Hb level was lowest in the presence of hookworms (7.1 g/dl [interquartile range {IQR} 6.8–7.5]), Schistosoma intercalatum (6.9 g/dl), Trichuris trichiura (10.1 g/dl [IQR 8.9–11.5]) and Plasmodium falciparum (10.0 g/dl [IQR 9.1–11.2]) compared with filariaemia (12.1 g/dl [IQR 10.5–13.2]) (p=0.03). Moderate to severe anaemia predominated among those single-infected with P. falciparum (69.5%) or co-infected with intestinal parasitic infections and P. falciparum (76.2%), while it was found in only 23.2% of individuals with filariasis. All participants with soil-transmitted helminths and more than half with a Blastocystis sp. (68.8%) infection had moderate anaemia.

Conclusions

The prevalence of anaemia is high. Asymptomatic parasite carriage is associated with anaemia in this surveyed population in Gabon.

Effect of immune regulatory pathways after immunization with GMZ2 malaria vaccine candidate in healthy lifelong malaria-exposed adults

BACKGROUND

Despite appreciable immunogenicity in malaria-naive populations, many candidate malaria vaccines are considerably less immunogenic in malaria-exposed populations. This could reflect induction of immune regulatory mechanisms involving Human Leukocyte Antigen G (HLA-G), regulatory T (Treg), and regulatory B (Breg) cells. Here, we addressed the question whether there is correlation between these immune regulatory pathways and both plasmablast frequencies and vaccine-specific IgG concentrations.

METHODS

Fifty Gabonese adults with lifelong exposure to Plasmodium spp were randomized to receive three doses of either 30 µg or 100 µg GMZ2-CAF01, or 100 µg GMZ2-alum, or control vaccine (rabies vaccine) at 4-week intervals. Only plasma and peripheral blood mononuclear cells isolated from blood samples collected before (D0) and 28 days after the third vaccination (D84) of 35 participants were used to measure sHLA-G levels and anti-GMZ2 IgG concentrations, and to quantify Treg, Breg and plasmablast cells. Vaccine efficacy was assessed using controlled human malaria infection (CHMI) by direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ Challenge).

RESULTS

The sHLA-G concentration increased from D0 to D84 in all GMZ2 vaccinated participants and in the control group, whereas Treg frequencies increased only in those receiving 30 µg or 100 µg GMZ2-CAF01. The sHLA-G level on D84 was associated with a decrease of the anti-GMZ2 IgG concentration, whereas Treg frequencies on D0 or on D84, and Breg frequency on D84 were associated with lower plasmablast frequencies. Importantly, having a D84:D0 ratio of sHLA-G above the median was associated with an increased risk of P. falciparum infection after sporozoites injection.

CONCLUSION

Regulatory immune responses are induced following immunization. Stronger sHLA-G and Treg immune responses may suppress vaccine induced immune responses, and the magnitude of the sHLA-G response increased the risk of Plasmodium falciparum infection after CHMI. These findings could have implications for the design and testing of malaria vaccine candidates in semi-immune individuals.

Prevalence of intestinal parasitic infection and associated factors among pregnant women attending antenatal care at public health facilities in Lalo Kile district, Oromia, Western Ethiopia

OBJECTIVE

This study aimed to assess the prevalence of intestinal parasitic infection and associated factors among pregnant women attending antenatal care at public health facilities in Lalo Kile district, Oromia, Western Ethiopia.

RESULTS

Out of the 315 respondents, the mean age was 24.7 ± 2.54 years ranging between 15 and 44 years. The majority of the respondents were Oromo in ethnicity (90.2%) and protestant in religion (83.2%) and almost all (99%) of the study participants were married. Two hundred twenty-six (72%) of pregnant women were attended at least primary school and two hundred forty-six (78.1%) of the respondents were from farmer households. About half of the households (51.7%) had a monthly income of greater than 35 USD. The overall prevalence of intestinal parasitic infection was 138 (43.8%) with the predominance of hookworm (33.7%) followed by Ascaris lumbricoides (7.3%). Being a farmer [AOR, 95% CI 7.3 (1.46, 37.00), P = 0.03], walking barefooted [AOR, 95% CI 6.13 (1.98, 19.00), P = 0.002] and absence of proper handwashing after latrine [AOR, 95% CI 5.36 (1.78, 16.00), P = 0.003] were significantly associated with occurrence of the intestinal parasitic infection.

Placental gene expression and antibody levels of mother-neonate pairs reveal an enhanced risk for inflammation in a helminth endemic country

In utero exposure to environmental factors can modify the development of allergies later in life whereby the mechanisms of the feto-maternal crosstalk still remain largely unknown. Murine studies revealed that inflammatory maternal signals elicited by chronic helminth infection within the placenta imprint a distinct gene expression profile related to the Vitamin-D-receptor (VDR)-inflammation-axis. We thus investigated whether pro- or anti- inflammatory immune responses as well as VDR and related gene expression within the placenta differ between women from helminth-endemic and non-endemic areas. A prospective pilot study was conducted in Munich, Germany (helminth non-endemic) and Lambaréné, Gabon (helminth-endemic). At delivery, clinical information alongside placenta tissue samples and maternal and cord blood were obtained for further laboratory analysis. Schistosoma haematobium infection was detected in 13/54 (23%) Gabonese women. RT PCR revealed significantly lower gene expression of VDR, Cyp27b1, Foxp3 and IL10 in Gabonese compared to German placentae as well as significantly lower levels of plasma IgG4 in newborns resulting in a significantly higher IgE/IgG4 ratio. These findings demonstrate that exposure in utero to different environments alters placental gene expression and thus possibly plays a role in the development and modulation of the immune system of the offspring.

Old friends and friendly fire: Pregnancy, hookworm infection, and anemia among tropical horticulturalists

OBJECTIVES

Despite public health concerns about hookworm infection in pregnancy, little is known about immune profiles associated with hookworm (Necator americanus and Ancylostoma duodenale) infection during pregnancy. Fetal tolerance requirements may constrain maternal immune response to hookworm, thereby increasing susceptibility to new infections or increasing hemoglobin loss. To explore this possibility, we study systemic immune response and hemoglobin levels in a natural fertility population with endemic helminthic infection.

METHODS

We used Bayesian multilevel models to analyze mixed longitudinal data on hemoglobin, hookworm infection, reproductive state, eosinophils, and erythrocyte sedimentation rate (ESR) to examine the effects of pregnancy and hookworm infection on nonspecific inflammation, cellular parasite response, and hemoglobin among 612 Tsimane women aged 15-45 (1016 observations).

RESULTS

Pregnancy is associated with lower eosinophil counts and lower eosinophil response to hookworm, particularly during the second and third trimesters. Both hookworm and pregnancy are associated with higher ESR, with evidence for an interaction between the two causing further increases in the first trimester. Pregnancy is moderately associated with higher odds of hookworm infection (OR: 1.23, 95% CI: 0.83 to 1.83). Pregnancy and hookworm both decrease hemoglobin and may interact to accentuate this effect in the first-trimester of pregnancy (Interaction: β: -0.30 g/dL; CI: -0.870 to 0.24).

CONCLUSIONS

Our findings are consistent with a possible trade-off between hookworm immunity and successful pregnancy, and with the suggestion that hookworm and pregnancy may have synergistic effects, particularly in the first trimester.

Prevalence and associated factors of soil transmitted helminthes among pregnant women attending antenatal care in Maytsebri primary hospital, North Ethiopia

OBJECTIVES

Soil-transmitted helminthes are among the most common infections worldwide and affect the poorest and most deprived communities. A health facility based cross-sectional study was conducted among pregnant women attending at Maytsebri primary hospital. Data was entered and analysed using SPSS version 20 software. Multivariate analyses were used to identify determinant factors associated with soil transmitted helminthiasis. A total of 448 pregnant women were examined microscopically with a Katokatz technique for parasitological study to each women.

RESULTS

Out of the total 448 pregnant women examined in the primary hospital, 229 (51.5%) women were infected by at least one of the soil transmitted helminthiasis. Hookworm was the most prevalent 179 (78.16%) soil transmitted helminthes infection. Women who had a habit of eating soil were 2.6 times more likely to be infected by soil transmitted helminthes compared to who do not eat soil. Participants who wear shoe always were 95% less likely to be infected by soil transmitted helminthes. Efforts should be done to advance the awareness of women how to prevent soil transmitted helminthes.

Maternal helminth infections and the shaping of offspring immunity

Helminth infections leave a long-lasting immunological footprint on their hosts. Clinical studies have provided first evidence that maternal helminth infections can result in an altered immune profile in their offspring which can potentially shape how they respond to conditions throughout life. This can relate to changes in offspring induction of immune responses against other diseases. However, whether these changes result in actual changes in offspring ability to control disease is unclear. Our understanding of which immune mechanisms are altered and how they are changed is limited. In this review, we highlight what we know from human and mouse studies about this important context of helminth exposure. Moreover, we discuss how mechanisms such as antibody transfer, antigen exposure, maternal cell uptake, chimerism and epigenetics are all likely to be functional contributors to the striking changes that are seen in offspring born or nursed by helminth exposed mothers.

Seroprevalence of Malaria and Hepatitis B Coinfection among Pregnant Women in Tamale Metropolis of Ghana: A Cross-Sectional Study

Background

Coinfections are becoming common risk factors that may contribute to the increased burden of morbidity in pregnancy. The aim of this study was to assess the seroprevalence of coinfections of malaria, hepatitis B (HBV), human immunodeficiency virus (HIV), and syphilis among pregnant women attending antenatal clinics (ANC) in the Tamale Metropolis.

Methods

By means of rapid diagnostic tests (RDTs), pregnant women attending the Tamale Teaching Hospital (TTH) were screened for malaria, HBV infection, HIV infection, and syphilis from March 2013 to February 2015. Haemoglobin (Hb) values, sickling, and glucose-6-phosphate dehydrogenase deficiency (G6PDd) statuses were also assessed using full blood count (FBC), sodium metabisulphite, and methaemoglobin reduction tests, respectively. Logistic regression analysis was performed to estimate the risks/odds ratios (ORs) for the coinfections and other variables (age, gravidity, and time of the first ANC visit) with 95% confidence intervals (CIs) and set p values for accepting any differences at <0.05.

Results

Within the two-year study period, data were collected from 3,127 pregnant women. The mean age (SD) of the pregnant women was 28.5 (±5.0) years. Of the total number, seroprevalence was high for malaria (11.6%) and HBV infection (4.2%) and low for HIV infection (1.0%) and syphilis (0.4%) monoinfections. Mal/HBV coinfection was higher (0.7%) when compared with Mal/HIV (0.1%), Mal/syphilis (0.0%), HBV/HIV (0.0%), HBV/syphilis (0.1%), and HIV/syphilis (0.0%) coinfections. The mean Hb (g/dl) for the women with the four monoinfections was significantly different from one another (p=0.009). Pregnant women with malaria infection were about 2 times more likely to be coinfected with HBV even after adjusting for potential confounders (adjusted odds ratio (AOR) = 1.66, 95% CI = 1.04-2.65, p=0.031). Those in their third trimester and visiting the ANC for the first time were significantly less likely to be infected with HBV (AOR = 0.45, 95% CI = 0.28-0.73, p=0.001), with malaria/HBV coinfection (AOR = 0.09, 95% CI = 0.01-0.68, p=0.020), and with any coinfection (AOR = 0.19, 95% CI = 0.06-0.63, p=0.007).

Conclusion

A comparatively high seroprevalence of malaria and its coinfection with HBV in pregnant women was observed in this study. Considering the effects that both malaria and HBV have on the liver, it would be expedient to conduct further studies to assess liver function among malaria/HBV-infected individuals, while interventions to prevent coinfections among pregnant women are intensified.

Prevalence and associated factors of Plasmodium falciparum and soil transmitted helminth infections among pregnant women in Osun state, Nigeria

BACKGROUND

Plasmodium falciparum and soil transmitted helminth (STHs) infection are widespread in sub-Sahara Africa, where co-infection is also common. This study assessed the prevalence of these infections and their risk factors among pregnant women in Osogbo, Nigeria.

METHODS

A total of 200 pregnant women attending the antenatal clinic were recruited. Plasmodium falciparum was detected using thick and thin film methods, while formol ether concentration method was used for STHs detection. A questionnaire was used to investigate the possible risk factors associated with acquisition of malaria and helminth infections.

RESULTS

The prevalence of P. falciparum, STHs and their co-infection was 29.5%, 12% and 5% respectively. P. falciparum, STHs and P. falciparum + STHs co-infection was significantly higher in primigravidae (52.5% vs 58.3% vs 80%) than in secongravidae (18.6% vs 25.0% vs 20%) and multigravidae (28.8% vs 16.7% vs 0%) (p=0.02). Prevalence associated factors identified for P. falciparum was age (p=0.0001) while gravidity (p=0.02) was identified for P. falciparum + STHs co-infection.

CONCLUSION

High prevalence of P. falciparum and helminth infections was observed among the pregnant women with primigravidae being the most susceptible to co-infection. There is an urgent need to implement an effective malaria and STHs preventive method for this high risk population.

Schistosoma haematobium effects on Plasmodium falciparum infection modified by soil-transmitted helminths in school-age children living in rural areas of Gabon

BACKGROUND

Malaria burden remains high in the sub-Saharan region where helminths are prevalent and where children are often infected with both types of parasites. Although the effect of helminths on malaria infection is evident, the impact of these co-infections is not clearly elucidated yet and the scarce findings are conflicting. In this study, we investigated the effect of schistosomiasis, considering soil-transmitted helminths (STH), on prevalence and incidence of Plasmodium falciparum infection.

METHODOLOGY

This longitudinal survey was conducted in school-age children living in two rural communities in the vicinity of Lambaréné, Gabon. Thick blood smear light microscopy, urine filtration and the Kato-Katz technique were performed to detect malaria parasites, S. haematobium eggs and, STH eggs, respectively. P. falciparum carriage was assessed at inclusion, and incidence of malaria and time to the first malaria event were recorded in correlation with Schistosoma carriage status. Stratified multivariate analysis using generalized linear model was used to assess the risk of plasmodium infection considering interaction with STH, and survival analysis to assess time to malaria.

MAIN FINDINGS

The overall prevalence on subject enrolment was 30%, 23% and 9% for S. haematobium, P. falciparum infections and co-infection with both parasites, respectively. Our results showed that schistosomiasis in children tends to increase the risk of plasmodium infection but a combined effect with Trichuris trichiura or hookworm infection clearly increase the risk (aOR = 3.9 [95%CI: 1.7-9.2]). The incidence of malaria over time was 0.51[95%CI: 0.45-0.57] per person-year and was higher in the Schistosoma-infected group compared to the non-infected group (0.61 vs 0.43, p = 0.02), with a significant delay of time-to first-malaria event only in children aged from 6 to 10-years-old infected with Schistosoma haematobium.

CONCLUSIONS

Our results suggest that STH enhance the risk for P. falciparum infection in schistosomiasis-positive children, and when infected, that schistosomiasis enhances susceptibility to developing malaria in young children but not in older children.

Plasmodium and intestinal parasite perturbations of the infected host's inflammatory responses: a systematic review

Co-infection of malaria and intestinal parasites is widespread in sub-Saharan Africa and causes severe disease especially among the poorest populations. It has been shown that an intestinal parasite (helminth), mixed intestinal helminth or Plasmodium parasite infection in a human induces a wide range of cytokine responses, including anti-inflammatory, pro-inflammatory as well as regulatory cytokines. Although immunological interactions have been suggested to occur during a concurrent infection of helminths and Plasmodium parasites, different conclusions have been drawn on the influence this co-infection has on cytokine production. This review briefly discusses patterns of selected cytokine (IL-6, IL-8, IL-10, TNF-α and INF-γ) responses associated with infections caused by Plasmodium, intestinal parasites as well as a Plasmodium-helminth co-infection.

Preliminary Evidence for the Absence of Cystic Echinococcosis in Gabon: A Cross-Sectional Pilot Survey in Humans and Definitive Hosts

Cystic echinococcosis (CE) is a globally endemic zoonosis caused by the larval stage of the Echinococcus granulosus sensu lato (s.l.) complex. Although the disease is known to be highly prevalent in certain parts of North and East Africa, data on CE, both in humans and definitive hosts, are extremely scarce for Central Africa. The present study assessed the epidemiology of CE in humans and dogs in rural Gabon. An ultrasound and serologic survey was conducted in volunteers from rural villages in Gabon. A two-step approach was used for serological testing with an indirect hemagglutination assay as a screening test and Western Blot as a confirmatory test. Fecal dog samples were analyzed microscopically, and polymerase chain reaction (PCR) amplification of nad1 and cox1 genes was performed when taeniid eggs were visible. Regional hospitals and the national reference center for parasitology in Gabon were contacted for information about previous cases of CE. Randomly selected communities were invited to participate. Three hundred and forty-eight human volunteers from these communities were screened. No suspected cases of CE were detected. Definitive host screening was performed from 128 fecal samples from representative subregions, but no eggs from E. granulosus s.l. were found. No documented cases of echinococcosis were reported from the local health-care institutions and the national diagnostic reference center in Gabon. Cystic echinococcosis seems to be very rare or absent in Gabon. The reason for this lack of evidence for echinococcosis is unknown, but the absence of livestock may play a major role.

Prevalence of and risk factors for malaria, filariasis, and intestinal parasites as single infections or co-infections in different settlements of Gabon, Central Africa

BACKGROUND

Malaria, filariasis, and intestinal parasitic infections (IPIs) are common and frequently overlap in developing countries. The prevalence and predictors of these infections were investigated in three different settlements (rural, semi-urban, and urban) of Gabon.

METHODS

During cross-sectional surveys performed from September 2013 to June 2014, 451 individuals were interviewed. In addition, blood and stool samples were analysed for the presence of Plasmodium, filarial roundworm, intestinal protozoan, and helminth infections.

RESULTS

Intestinal parasitic infections (61.1%), including intestinal protozoa (56.7%) and soil-transmitted helminths (STHs) (22.2%), predominated, whereas Plasmodium falciparum (18.8%), Loa loa (4.7%), and Mansonella perstans (1.1%) were less prevalent. Filariasis and STHs were mainly found in rural settlements, whereas a higher plasmodial infection prevalence rate was observed in the periurban area. The most common IPI was blastocystosis (48.6%), followed by ascaridiasis (13.7%), trichuriasis (11.8%), amoebiasis (9.3%), giardiasis (4.8%), and strongyloidiasis (3.7%). Hookworm was detected in one adult from rural Dienga. Adults had a higher prevalence of Blastocystis hominis and STHs, whereas Giardia duodenalis was more frequently observed among children aged below 5 years (P < 0.01). The polyparasitism rate was 41.5%, with 7.0% Plasmodium-IPIs and 1.8% Plasmodium-STH co-infections. The multivariate analysis showed that living in a suburban area, belonging to the age group of 5-15 years, having none or a secondary education, or having an open body water close to home were significant risk factors for malaria (P ≤ 0.01). For STH infections, identified risk factors were drinking untreated water and living in a rural area (P ≤ 0.04). No significant predictors were identified for IPIs and malaria-IPI co-infection.

CONCLUSIONS

This study reports a high prevalence of IPIs and intestinal protozoa, but a low rate of malaria-IPI co-infections in the study sites. Improvements in the living conditions of the population such as adequate water supply and proper health education and sanitation should be integrated into control strategies for malaria, STHs, and IPIs.

Maternal urogenital schistosomiasis; monitoring disease morbidity by simple reagent strips

Background

Urine analysis is one of the recommended antenatal guidelines for early diagnosis of pregnancy-associated complications. While in practice, urine analysis by dipstick had been used to provide useful information on other urinary tract infections, its applications for early detection of urogenital schistosomiasis in pregnant women is often times not given due attention in most endemic areas. Our study therefore assessed the performance of some common urinalysis parameters in the diagnosis of maternal urogenital schistosomiasis in endemic rural communities of Nigeria.

Methodology/Principal findings

The cross-sectional epidemiologic survey of urogenital schistosomiasis was conducted among pregnant women in Yewa North Local Government, Ogun State, Nigeria. The women were microscopically examined for infection with Schistosoma haematobium, visually observed for macrohematuria, and screened for microhematuria and proteinuria using standard urine chemical reagent strips. Of 261 volunteered participants, 19.9% tested positive for S. haematobium infection. The proportion of microhematuria (23.8%) was significantly higher than that of macrohematuria (3.8%) and proteinuria (16.8%) (P<0.05). Microhematuria with sensitivity (82.7%) and specificity (89.0%) was the best diagnostic indicator of urogenital schistosomiasis. Macrohematuria with the least sensitivity (11.8%) was however the most specific (98.1%) for diagnosing urogenital schistosomiasis in pregnant women. Maximum microhematuria sensitivity (100.0%) was observed in women between 15–19 years but sensitivity was consistently low in older age groups. Maximum sensitivity, specificity and predictive values (100.0%) were recorded for microhematuria in first trimester women. Diagnostic efficiency of proteinuria and macrohematuria was also better in the first trimester women except the 25.0% specificity recorded for proteinuria. The overall diagnostic performance of microhematuria and proteinuria was better in secundigravidae.

Conclusions/Significance

Microhematuria can be used for early detection of urogenital schistosomiasis in endemic areas especially in younger women. However because microhematuria is a condition that occurs during pregnancy and in several other diseases, it is necessary to compliment the diagnosis with other diagnostic tools such as microscopy and serology. Treatment with praziquantel is recommended for the women in their late trimesters after follow up test in order to avert associated adverse pregnancy outcomes.

Demography, maternal health and the epidemiology of malaria and other major infectious diseases in the rural department Tsamba-Magotsi, Ngounie Province, in central African Gabon

BACKGROUND

Sub-Saharan Africa is undergoing an epidemiological transition from a predominance of infectious diseases to non-communicable and lifestyle related conditions. However, the pace of this transition and the pattern of disease epidemiology are uneven between affluent urban and rural poor populations. To address this question for a remote rural region located in the central African rainforest region of Gabon, this study was conducted to assess reasons for health care attendance and to characterize the epidemiology of malaria and other major infectious diseases for the department of Tsamba Magotsi.

METHODS

Major causes for health care attendance were collected from local hospital records. Cross sectional population based surveys were performed for the assessment of local malaria epidemiology. Pregnant women attending antenatal care services were surveyed as a sentinel population for the characterization of chronic viral and parasitic infections in the community.

RESULTS

Infectious diseases were responsible for 71% (7469) of a total of 10,580 consultations at the formal health care sector in 2010. Overall, malaria - defined by clinical syndrome - remained the most frequent cause for health care attendance. A cross sectional malaria survey in 840 asymptomatic individuals residing in Tsamba Magotsi resulted in a Plasmodium spp. infection prevalence of 37%. The infection rate in 2-10 year old asymptomatic children - a standard measure for malaria endemicity - was 46% (100 of 217) with P. falciparum as predominant species (79%). Infection with other plasmodial species (P. ovale and P. malariae) presented most commonly as coinfections (23.2%). Prevalence of HIV, HBV, and syphilis were 6.2, 7.3, and 2.5%, respectively, in cross-sectional assessments of antenatal care visits of pregnant women. Urogenital schistosomiasis and the filarial pathogens Loa loa and Mansonella perstans are highly prevalent chronic parasitic infections affecting the local population.

CONCLUSIONS

Despite major improvements in the accessibility of Tsamba Magotsi over the past decade the epidemiological transition does not appear to have majorly changed on the spectrum of diseases in this rural Gabonese population. The high prevalence of Plasmodium infection indicates a high burden of malaria related morbidity. Infectious diseases remain one of the most important health issues and further research activities in the field of tropical medicine and infectious diseases could help improve health care for the local population.

Urogenital schistosomiasis during pregnancy is associated with low birth weight delivery: analysis of a prospective cohort of pregnant women and their offspring in Gabon

An estimated 40 million women of childbearing age suffer from schistosomiasis. Animal models indicate a deleterious effect of maternal schistosomiasis on pregnancy outcomes. To date there is a lack of epidemiological evidence evaluating schistosomiasis-related morbidity in pregnancy. This study was designed to describe the impact of urogenital schistosomiasis on pregnancy outcomes in a highly endemic region of central Africa. Pregnant women attending antenatal clinics in Fougamou and Lambaréné, Gabon, were consecutively screened for the presence of Schistosoma haematobium eggs in diurnal urine samples. Maternal and newborn characteristics assessed at delivery were compared between infected and uninfected mothers. The impact of maternal schistosomiasis on low birth weight and preterm delivery was assessed using logistic regression analysis. Urogenital schistosomiasis was diagnosed in 103 (9%) of 1115 pregnant women. Maternal age was inversely associated with the prevalence of urogenital schistosomiasis, with a higher burden amongst nulliparous women. Low birth weight was more common amongst infants of S. haematobium-infected mothers. This association was unaffected by controlling for demographic characteristics, gestational age and Plasmodium infection status (adjusted Odds Ratio 1.93; 95% confidence interval: 1.08-3.42). Other risk factors associated with low birth weight delivery were underweight mothers (adjusted Odds Ratio 2.34; 95% confidence interval: 1.12-4.92), peripheral or placental Plasmodium falciparum infection (adjusted Odds Ratio 2.04; 95% confidence interval: 1.18-3.53) and preterm birth (adjusted Odds Ratio 3.12; 95% confidence interval: 1.97-4.96). Preterm delivery was not associated with S. haematobium infection (adjusted Odds Ratio 1.07 95% confidence interval: 0.57-1.98). In conclusion, this study indicates that pregnant women with urogenital schistosomiasis are at an increased risk for low birth weight deliveries. Further studies evaluating targeted treatment and prevention programmes for urogenital schistosomiasis in pregnant women and their impact on delivery outcomes are warranted.

Helminth infection during pregnancy: insights from evolutionary ecology

Helminths are parasitic nematodes and trematodes, grouped together because of morphological similarities and commonalities in the effects infections have on hosts. These include complications such as anemia and biasing of immune responses, which can alter susceptibility for other diseases. For pregnant women, these complications might have implications for pregnancy outcomes or neonatal health. Here, I review studies of helminth infections during pregnancy, and ask the following questions: Do helminths affect maternal health or pregnancy outcomes? Are there consequences of maternal infection for infants? What are the effects of antihelminth treatment during pregnancy? The evidence suggests that the answers to these questions depend on the particular helminth species in question, maternal nutritional status, and the presence or absence of comorbid infection with other species, such as malaria. Moreover, there may also be unexpected consequences of treatment, as maternal infections can affect the priming of infant immune systems, with potential effects on infants later in life. These complex interactions suggest that a consideration of the evolutionary history of human–helminth interactions, as well as the ecological context of infections, can help to clarify an understanding of these host–parasite interactions and provide direction for future investigations.

Prevalence of intestinal parasitic infections and associated risk factors among pregnant women attending antenatal care center at Felege Hiwot Referral Hospital, northwest Ethiopia

BACKGROUND

Parasitic infections affect tens of millions of pregnant women worldwide, and directly or indirectly lead to a spectrum of adverse maternal and fetal/placental effects. The objective of this study was to assess the prevalence of intestinal parasite infections and associated risk factors among pregnant women attending antenatal care center in Felege Hiwot Referral Hospital, Bahir Dar city, northwest Ethiopia.

METHODS

A cross-sectional hospital based study was conducted from November 2013 to January 2014 among 384 pregnant women. Stool samples were examined for the presence of trophozoites, cysts, oocysts, and ova using direct, formal-ether sedimentation, and modified Ziehl-Neelsen techniques.

RESULTS

An overall prevalence of 31.5 % intestinal parasite infections was recorded. Eight different species of intestinal parasites were found: two protozoan and six helminth species. The highest prevalence was due to Giardia lamblia (13.3 %) followed by Entamoeba histolytica/dispar (7.8 %), hookworm (5.5 %), Ascaris lumbricoides (2.9 %), Schistosoma mansoni (2.9 %), Strongyloides stercoralis (1.6 %), Taenia spp. (0.8 %), and Hymenolepis nana (0.3 %).

CONCLUSIONS

A relatively high prevalence of intestinal parasite infections was observed among pregnant women. Routine stool examination and provision of health education are required for early medical intervention that would affect the pregnant mothers and their foetuses.

Seroprevalence of Toxocara spp. in a rural population in Central African Gabon

Toxocara spp. are zoonotic parasites with global distribution infecting humans by incidental ingestions of eggs shed in feces of dogs or cats. High seroprevalences have been reported from several regions of Africa, however data from the Central African region remain limited. Although several clinical entities caused by larvae of Toxocara spp. have been described, the public heath impact of this infection has so far often been neglected. This study was conducted to estimate the prevalence in a rural central African population. The population based study was performed in volunteers in a rural region of Gabon. A two-step testing approach was applied using an ELISA as screening test and a Western Blot (immunoblot) as confirmatory assay. Basic demographic data and risk factors were collected and compared between seropositive and negative participants. In total, 199 out of 332 serum samples were tested positive for Toxocara spp. antibodies (59.9%). After standardization for age to the overall Gabonese population seroprevalence was 53.6% (95% CI 48.2-59.0%). There was a trend towards higher seroprevalence in participants with agricultural activity. Seroprevalence of antibodies against Toxocara spp. is high in this rural population in Gabon. These results are comparable with previous reports from other sub-regions of Africa and add to our understanding of the epidemiology of toxocariasis in Africa. Given the high prevalence of toxocariasis in tropical regions, it may be speculated that clinically relevant presentations (e.g. visceral or ocular larva migrans syndrome) may occur in considerable numbers. A formal assessment of the burden of disease and the public health impact of human toxocariasis is therefore warranted.

Associations Between Helminth Infections, Plasmodium falciparum Parasite Carriage and Antibody Responses to Sexual and Asexual Stage Malarial Antigens

Infections with helminths and Plasmodium spp. overlap in their geographical distribution. It has been postulated that helminth infections may influence malarial transmission by altering Plasmodium falciparum gametocytogenesis. This cross-sectional study assessed the effect of helminth infections on P. falciparum gametocyte carriage and on humoral immune responses to sexual stage antigens in Gabon. Schistosoma haematobium and filarial infections as well as P. falciparum asexual forms and gametocyte carriage were determined. The antibody responses measured were to sexual (Pfs230, Pfs48/45) and asexual P. falciparum antigens (AMA1, MSP1, and GLURP). A total of 287 subjects were included. The prevalence of microscopically detectable P. falciparum asexual parasites was higher in S. haematobium-infected subjects in comparison to their uninfected counterparts (47% versus 26%, P = 0.003), but this was not different when filarial infections were considered. Plasmodium falciparum gametocyte carriage was similar between Schistosoma- or filaria-infected and uninfected subjects. We observed a significant decrease of Pfs48/45 immunoglobulin G titer in S. haematobium-infected subjects (P = 0.037), whereas no difference was seen for Pfs230 antibody titer, nor for antibodies to AMA1, MSP1, or GLURP. Our findings suggest an effect of S. haematobium on antibody responses to some P. falciparum gametocyte antigens that may have consequences for transmission-blocking immunity.

Magnitude of Maternal Anaemia in Rural Burkina Faso: Contribution of Nutritional Factors and Infectious Diseases

Background. Maternal anaemia is a worldwide public health problem affecting particularly developing countries. In Burkina Faso, little data is available for rural areas. This study aimed to determine the prevalence of maternal anaemia and the risk factors associated with it in the rural health district of Hounde in Burkina Faso but also to define better control measures of maternal anaemia.Methods. This cross-sectional study conducted in 2010 had a sample of 3,140 pregnant women attending antenatal care in all the 18 primary health care facilities of the district. The women’s characteristics and their knowledge about contraceptives and sexually transmitted infections (STI) were collected. Also, physical and gynaecological examination, completed by vaginal, cervix, blood, and stool samplings, were collected.Results. A prevalence of 63.1% was recorded for maternal anaemia. Geophagy rate was 16.3% and vitamin A deficiency 69.3%. In addition, anaemia was independently associated with low education, low brachial perimeter, geophagy, and primigravida. But no statically significant relationship was found between maternal anaemia and infectious diseases or vitamin A deficiency.Conclusion. The magnitude of maternal anaemia was found to be higher in rural Hounde health district and should be addressed by adequate policy including education and the fight against malnutrition.

Prevalence and risk factor assessment of Tropheryma whipplei in a rural community in Gabon: a community-based cross-sectional study

Tropheryma whipplei is the causative agent of Whipple's disease and has been detected in stools of asymptomatic carriers. Colonization has been associated with precarious hygienic conditions. There is a lack of knowledge about the epidemiology and transmission characteristics on a population level, so the aim of this study was to determine the overall and age-specific prevalence of T. whipplei and to identify risk factors for colonization. This molecular epidemiological survey was designed as a cross-sectional study in a rural community in Central African Gabon and inhabitants of the entire community were invited to participate. Overall prevalence assessed by real-time PCR and sequencing was 19.6% (95% CI 16-23.2%, n=91) in 465 stool samples provided by the study participants. Younger age groups showed a significantly higher prevalence of T. whipplei colonization ranging from 40.0% (95% CI 27.8-52.2) among the 0-4 year olds to 36.4% (95% CI 26.1-46.6) among children aged 5-10 years. Prevalence decreased in older age groups (p<0.001) from 12.6% (95% CI 5.8-19.4%; 11-20 years) to 9.7% (95% CI 5.7-13.6) among those older than 20. Risk factor analysis revealed young age, male sex, and number of people sharing a bed as factors associated with an increased risk for T. whipplei carriage. These results demonstrate that T. whipplei carriage is highly prevalent in this part of Africa. The high prevalence in early life and the analysis of risk factors suggest that transmission may peak during childhood facilitated through close person-to-person contacts.